<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> 
    <title>第六课 数据类型</title>
</head> 
<body>
    <script>
        // var obj = new Object();
        // alert(typeof obj);
        // var obj = {
        //     name:'huawei',
        //     model:'meta20',
        //     price:200,
        //     playGame:function(){
                
        //     },
        //     callNumber:function(){

        //     },
        //     sendMessage:function(){

        //     }
        // };
        // alert(obj.name);
        // var obj = null;
        // alert(typeof obj);
        // var timer = null;
        // timer = setInterval(function(){},1000);
        alert(undefined == null);
    </script>                   
</body> 
</html>